You need to convert them to .blp files. Save them as .tga files in Photoshop, and download a converter here on the Hive (I recommend WC3Viewer, 'cause that's the only one I have experience with and know works). You import the .blp files to WE, and it should work. (I don't know what size icons are, so I can't tell if 64x64 is wrong).